WDCreech· Grumpy Old Goat Herder
The 3.25" main blocks are NOT as strong! The cranks are, but that is a moot point. I had a 455 block start to split after only about 150 1/4 mile passes. I had put a lot of time, and money, into this block to keep from having this kind of failure, but to no avail.The 455 blocks aren't as strong; I believe 455 cranks are strong, albeit the large journal diameter drives up bearing speed for a given rpm. But that's a different issue than strength IMHO.